Vanguard discloses 2.72M-share stake in Affiliated Managers Group (AMG)

Rhea-AI Filing Summary

Affiliated Managers Group Inc received an amended Schedule 13G/A filing from The Vanguard Group reporting beneficial ownership of 2,723,566 shares of common stock, equal to 10.2% of the class. The filing notes shared voting power of 218,781 shares and shared dispositive power of 2,723,566 shares.

The filing discloses an internal realignment at The Vanguard Group, Inc. effective 01/12/2026, after which certain subsidiaries or business divisions may report beneficial ownership separately.

Insights

Institutional Ownership Analyst

Vanguard reports a 10.2% stake with shared voting and dispositive power.

The filing lists 2,723,566 shares beneficially owned and indicates shared voting power of 218,781 and shared dispositive power of 2,723,566. These figures are presented as current ownership in the amendment.

The filing also records an internal reorganization at 01/12/2026 that may cause future disaggregated reporting by subsidiaries; timing for any separate reports is not shown in the excerpt.

Corporate Governance Specialist

Realignment may change future reporting but does not alter the disclosed stake now.

The amendment states the internal realignment at 01/12/2026 and that subsidiaries "will report beneficial ownership separately (on a disaggregated basis)" in reliance on the cited SEC release. The statement is a procedural disclosure.

Any subsequent disaggregated filings by Vanguard subsidiaries would be separate submissions; this amendment does not quantify those future filings.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 14)

Affiliated Managers Group Inc

(Name of Issuer)

Common Stock

(Title of Class of Securities)

02/27/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

SCHEDULE 13G

CUSIP Number(s):

1

Names of Reporting Persons

The Vanguard Group

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

PENNSYLVANIA

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 218,781.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,723,566.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,723,566.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

10.20 %

12

Type of Reporting Person (See Instructions)

IA

Comment for Type of Reporting Person: On January 12, 2026, The Vanguard Group, Inc. went through an internal realignment. As of that date, The Vanguard Group, Inc. no longer performs portfolio management services or administers proxy voting. In accordance with SEC Release No. 34-39538 (January 12, 1998), The Vanguard Group, Inc. anticipates that certain subsidiaries or business divisions of subsidiaries of The Vanguard Group, Inc., that currently have, or are deemed to have, beneficial ownership with The Vanguard Group, Inc., will report beneficial ownership separately (on a disaggregated basis) from The Vanguard Group, Inc. in reliance on such release. These subsidiaries and/or business divisions pursue the same investment strategies as previously pursued by The Vanguard Group, Inc. prior to the realignment.

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Affiliated Managers Group Inc
(b)	Address of issuer's principal executive offices: 600 Hale Street, Prides Crossing, MA, 01965
Item 2.
(a)	Name of person filing: The Vanguard Group
(b)	Address or principal business office or, if none, residence: 100 Vanguard Blvd., Malvern, PA 19355
(c)	Citizenship: PA
(d)	Title of class of securities: Common Stock
(e)	CUSIP No.: 008252108
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 2723566
(b)	Percent of class: 10.2 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 0
	(ii) Shared power to vote or to direct the vote: 218781
	(iii) Sole power to dispose or to direct the disposition of: 0
	(iv) Shared power to dispose or to direct the disposition of: 2723566
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required. The Vanguard Group, Inc.'s clients, including investment companies registered under the Investment Company Act of 1940 and other managed accounts, have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the securities reported herein. No one other person's interest in the securities reported herein is more than 5%.
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

The Vanguard Group

Signature:	Ashley Grim
Name/Title:	Head of Global Fund Administration
Date:	03/05/2026

FAQ

What stake does The Vanguard Group report in AMG?

The Vanguard Group reports beneficial ownership of 2,723,566 shares, representing 10.2% of AMG's common stock, with shared voting power on 218,781 shares.

Does Vanguard have sole voting or dispositive power over AMG shares?

No sole voting or dispositive power is reported. The filing states 0 shares for sole voting and sole dispositive power, with shared powers reported as disclosed.

When did Vanguard's internal realignment occur?

The internal realignment took effect on January 12, 2026. The filing says certain subsidiaries may report beneficial ownership separately following that realignment.

Will Vanguard's subsidiaries report their holdings separately?

The filing states subsidiaries or business divisions "will report beneficial ownership separately (on a disaggregated basis)." The amendment cites SEC Release No. 34-39538 as the rationale.

Who signed the Schedule 13G/A amendment for Vanguard?

The amendment was signed by Ashley Grim, identified as Head of Global Fund Administration, with the signature dated 03/05/2026.